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scsi: ufs-qcom: Delay specific time before gate ref clk

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After enter hibern8, as UFS JEDEC ver 3.0 requires, a specific gating wait
time is required before disable the device reference clock. If it is not
specified, use the old delay.

Link: https://lore.kernel.org/r/1581392451-28743-8-git-send-email-cang@codeaurora.org
Reviewed-by: Asutosh Das <asutoshd@codeaurora.org>
Reviewed-by: Hongwu Su <hongwus@codeaurora.org>
Signed-off-by: Can Guo <cang@codeaurora.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Can Guo 2020-02-10 19:40:50 -08:00 committed by Martin K. Petersen
parent 09f17791e6
commit 1cbadd0c33
1 changed files with 19 additions and 3 deletions
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20
drivers/scsi/ufs/ufs-qcom.c
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@ -843,11 +843,27 @@ static void ufs_qcom_dev_ref_clk_ctrl(struct ufs_qcom_host *host, bool enable)
/*
* If we are here to disable this clock it might be immediately
* after entering into hibern8 in which case we need to make
* sure that device ref_clk is active at least 1us after the
* sure that device ref_clk is active for specific time after
* hibern8 enter.
*/
if (!enable)
if (!enable) {
unsigned long gating_wait;
gating_wait = host->hba->dev_info.clk_gating_wait_us;
if (!gating_wait) {
udelay(1);
} else {
/*
* bRefClkGatingWaitTime defines the minimum
* time for which the reference clock is
* required by device during transition from
* HS-MODE to LS-MODE or HIBERN8 state. Give it
* more delay to be on the safe side.
*/
gating_wait += 10;
usleep_range(gating_wait, gating_wait + 10);
}
}
writel_relaxed(temp, host->dev_ref_clk_ctrl_mmio);